To get a glimpse into how you think on your feet while also providing top notch service, your interviewer is posing this tricky scenario to you. As you discuss how you would talk to them in a friendly yet professional tone, make sure you talk about the need to refer to the Air New Zealand policies regarding this situation. While it isn't important to know the exact policies of Air New Zealand, it is important that you point out to your interviewer that you would be aware of the policy if you were hired as their next Customer Service Agent, and that you would clearly communicate that policy to the customer. If you have been in a similar type of customer service situation in the past, don't hesitate to talk about how you handled that situation, as well.